The present invention is related to an environmental control system. More particularly, the present invention is related to a controller which stores diagnostic information related to the control of an environment or the operation of damper systems utilized in an environment control network.
Environment control networks or facility management systems are employed in office buildings, manufacturing facilities, and the like, for controlling the internal environment of the facility. The environment control network may be employed to control temperature, airflow, humidity, lighting, or security in the internal environment.
In environment control networks, controlled air units (variable air volume (VAV) boxes or unitary devices (UNT)) are located throughout the facility and provide environmentally controlled air to the internal environment. The controlled air is provided at a particular temperature or humidity so that a comfortable internal environment is established. The air flow rate of the controlled air is preferably measured in cubic feet per minute (CFM).
The VAV boxes are coupled to an air source which supplies the controlled air to the VAV box via duct work. VAV boxes and unitary devices provide the controlled air through a damper. The damper regulates the amount of the controlled air provided to the internal environment. The damper is coupled to an actuator which preferably positions the damper so that appropriate air flow (in CFM) is provided to the internal environment.
A controller is generally associated with at least one actuator and damper. The controller receives information related to the air flow and temperature in the internal environment and appropriately positions the actuator so that the appropriate air flow is provided to the internal environment. The controller may include sophisticated feedback mechanisms such as proportional integral (PI) control algorithms. Sophisticated feedback mechanisms allow the actuator to be positioned more precisely.
The controller may be coupled to a communication bus within the environment control network and is able to communicate with other components within the environment control network. For example, the controller may include circuitry which indicates when the controller has experienced a catastrophic malfunction. A message indicative of this malfunction may be communicated to components within the network across the communication bus. Also, the controllers may receive hazardous warning messages on the communication bus, such as a fire warning. The controller may be configured to close all dampers in response to a fire warning. Thus, the controllers are generally capable of receiving and transmitting information and messages from other components within the environment control network.
Large buildings typically have hundreds of controlled air units (VAV boxes and unitary devices) which are positioned in hard to reach and visually obstructed places. Service people in charge of repairing controllers and associated actuators receive complaints of a most general nature about the internal environment and are required to find the controlled air units which are responsible for the complaints. Once the hidden units are found, the service people must uncover the units and manually perform diagnostics for the units and the associated controllers by manipulating controls on the units and controllers.
Although service people are able to periodically perform diagnostic tests as described above, they are completely unaware of the ordinary operation of the controller and controlled air unit. For example, the service people have no information about the duty cycle of the actuator, the temperature error in the environment, airflow error, or controller run time when the service people are away. Conventional environmental networks have not included a diagnostic system for automatically and periodically recording summary data indicative actuator positions, temperature error, and airflow rate error over time. Thus, there is a need for a controller configured to store data associated with the lifetime operation of the controlled air unit and associated controller.